The sulphate obtained, the sulphuric acid could then be extracted.
This was the object to be attained.

Sulphuric acid is one of the agents the most frequently employed, and the manufacturing importance of a nation can be measured by the consumption which is made of it.

This acid would later be of great use to the settlers, in the manufacturing of candles, tanning skins, etc., but this time the engineer reserved it for another use.
Cyrus Harding chose, behind the Chimneys, a site where the ground was perfectly level.

On this ground he placed a layer of branches and chopped wood, on which were piled some pieces of shistose pyrites, buttressed one against the other, the whole being covered with a thin layer of pyrites, previously reduced to the size of a nut.
This done, they set fire to the wood, the heat was communicated to the shist, which soon kindled, since it contains coal and sulphur.

Then new layers of bruised pyrites were arranged so as to form an immense heap, the exterior of which was covered with earth and grass, several air-holes being left, as if it was a stack of wood which was to be carbonized to make charcoal.
They then left the transformation to complete itself, and it would not take less than ten or twelve days for the sulphuret of iron to be changed to sulphate of iron and the alumina into sulphate of alumina, two equally soluble substances, the others, flint, burnt coal, and cinders, not being so.
While this chemical work was going on, Cyrus Harding proceeded with other operations, which were pursued with more than zeal,--it was eagerness.
Neb and Pencroft had taken away the fat from the dugong, and placed it in large earthen pots.